The present invention relates to a switching regulator for use in a power supply system for an electric computer.
In the conventional power supply systems for the electric computers, the AC voltage is stepped down by a transformer and rectified, and the current and voltage to be applied to a load are controlled by power transistors in a control unit. The variation both in load and input is compensated by the voltage stored in the power transistors. Therefore, when the load is increased, the voltage stored in the power transistor is increased so that the heat dissipation (the magnitude of which is the product of the stored voltage with the load current) occurs, thus resulting in the considerable loss in energy.
In order to overcome the above problem, the same inventors proposed the switching regulator of the type in which the input from the power supply is converted into the high frequency pulses whose pulse duration is changed depending upon the variation in load, whereby the power supply may be varied in response to the variation in load. In the switching regulator of the type described, however, the voltage which is derived by stepping down the power supply voltage by a low frequency transformer is used as the driving voltage for the pulse duration changing unit. Since the low frequency transformer used is large in size and heavy in weight, the switching regulator itself becomes large in size and heavy in weight. Furthermore, the power supply voltage is stepped down so that the magnitudes of the currents flowing through the various circuits are high, resulting in the thermal losses that cannot be neglected and in the decrease in overall efficiency.